1. Field of the Invention
This invention relates to a machine contour grinding outside peripheral surfaces of workpieces, particularly to means for supplying a cooling and lubricating fluid in such a machine, which comprises a grinding wheel that is covered by a guard hood and in which said means for supplying a cooling and lubricating fluid comprise a nozzle, which flares toward the peripheral surface of the grinding wheel and is open toward said peripheral surface and on that side which faces opposite to the direction of rotation of the grinding wheel is provided with a lip, which is adjustable toward and away from said peripheral surface.
2. Description of the Prior Art
In the contour grinding of outside peripheral surfaces of workpieces the quantity of heat generated in the contact zone between the grinding wheel and the workpiece must be minimized and must be dissipated as fast and as completely as possible by a coolant. For this reason a cooling and lubricating fluid is supplied to said contact zone. As the surface speed of the grinding wheel increases, the ingress of said fluid into the nip between the grinding wheel and the workpiece is progressively opposed by the cushion of air which surrounds the grinding wheel. In known systems the cooling and lubricating fluid is discharged from nozzlelike orifices under high pressure and at a high volume flow rate so that the fluid can penetrate through said air cushion.
It is known that this can be accomplished by the use of free-jet nozzles or thrust nozzles. Free-jet nozzles discharge a freely flowing jet of cooling and lubricating fluid and said jet owing to its high velocity is intended to penetrate at a suitable location the air cushion which surrounds the grinding wheel. That object can be accomplished only by the provision of an expensive structure. Thrust nozzles substantially conform to the curvature of the peripheral surface of the grinding wheel and are closed on all sides except for an opening which faces the peripheral surface of the grinding wheel so that the cooling and lubricating fluid can more effectively enter the boundary layer of air. But thrust nozzles will become increasingly less effective as the diameter of the grinding wheel is decreased by wear.
From Published German Application 20 23 200 it is further known to provide a nozzle which flares toward and is open to the grinding wheel and the extends over the width of the grinding wheel and is provided on that side which faces opposite to the direction of rotation of the grinding wheel with a lip, which is adjustable toward and away from the peripheral surface of the grinding wheel and adapted to inhibit the formation of an air cushion on said peripheral surface adjacent to said nozzle.